Drop leg and coupler interlock for trailers



arch 25, 1947. W BENNETT I 2,417,903

DROP LEG AND COUPLER INTERLOCK FOR TRAILERS 4 Shets- Sheet l C,lao

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vw. BENNETT DROP LG AND COUPLER INTERLOCK FOR TRAILERS Filed Feb. 24, 1945 sheets-sheet 2 l arch 25, r1947.- W BENNETT l 2,417,903 l DROP LEG AND COUPLER INTERLCK FOR TRAILERS File Feb. 24, 1945 4 sheets-sheet 5 March 25, 194'?. w. BENNETT l 2,437,903

DROP LEG AND COUPLER INTERLOCK FOR 'TRAILERS I Filed Feb. 24, 1945 lIl Sheets-Sheet -4 Mfr A A A .inve-'172102- Patented Mar. 25, i947 DROP LEG AND COUPLER, INTERLOCK FOR TRAILERS Walter Bennett, Los Angeles, Calif., assigner to Utility Trailer Manufacturing Company, Los Angeles, Calif., a corporation of California Application February 24, 1945, Serial No. 579,569

29 Claims. 1

Thisinvention relates primarily to improvements in supports for semi-trailers and to a cooperation and interlocking of the improved support with a trailer coupler or draft lock; and the general purpose of the invention is to provide an improved type of support, and improved cooperative functioning with a trailer coupler, characterized by ruggedness and simplicity of structure and dependability of operation. Further objects and corresponding accomplishments of the invention will be understood from the following'description of typical forms which embody the invention.

The typical form of support herein illustrated as an embodiment of the invention is of the drop leg type. A somewhat similar drop leg is shown in the application of Robert M. Barnhart, et al., Ser. No. 464,777 which was led November 6, 1942, now Patent No. 2,374,320 granted Apr. 24, 1945. In that support the arrangement is such that the movement of 4lowering the support is followed by a nal locking movement which locks the support in its lowered operative position; and that nal locking movement is utilized for the purpose of unlocking the trailer coupler. The

operation there is such that the draft lock cannot be nally released until the support is in its supporting condition; and then the support cannot be raised until the coupler is subsequently closed.

By way of comparison (although this comparison is not intended to fully describe the novel feature of my improved support and its combination with a draft lock) I provide in my improved support an arrangement whereby the movable member of the support (the drop leg) may be positively locked in any one of a number of lower positions, and then I provide a cooperative arrangement whereby the draft lock, which has been initially released by lowering ofthe support, will positively force the locking of the support in any, or at least one, of its several lower positions by virtue of the coupler being forced open. It is one of the features of my present invention that the locking of the leg in a supporting condition is positively forced by the motion of theking pin in opening the coupler, or the motion of the coupler to free the king pin; and that the locking of the support is positive 'and not dependent on springs or other yielding elements.

The draft lock mechanism which is illustrated herein is, in and'of itself and in combination with other orgeneric forms of support, the subjectmatter of my copending application, Ser.V No. 579,570, led on even date herewith. The present application is directed to my improvements in support per se and to the cooperative combination of my improved support with a draft lock of the general type herein illustrated.

For the purpose of .the following detailed description of typical forms embodying the invention reference is had to the accompanying drawings in which Fig. 1 is a plan showing the forward end of a typical semi-trailer frame equipped with the draft lock, shown in closed locked position;

Fig. 2 is a similar View showing the `draft lock in open position;

Fig. 3 is a detail section taken as indicated by line 3-3 on Fig. 1 and showing the parts in position corresponding to the dotted line showing in Fig. 1; Y

Fig. 4 is an elevational section looking at the parts from the rear showing the application of my improved supports, in typical form, to the trailer, certain details being omitted from this figure for purposes of simplicity and clarity;

Fig. 5 is an enlarged vertical section and elevation taken as indicated by line 5-5 on Fig. 4, and showing the support in a lower position;

Fig. 6 is a view, partly in section and partly in elevation, with the section taken as indicated by lines 6 6 on Figs. 5 and 7;

Fig. 7 is a section taken as indicated by line 1-1 on Fig. 6, and with certain parts in elevation;

Fig. 7A is a diagram'illustrating various positions of certain parts shown in Fig. 7;

Fig. 8 is a section similar to that of Fig, 7 but showing the support raised;

Fig. 9 is an enlarged detail section taken as indicated by lines 9 9 on Figs. 6 and 10;

Fig. 10 is a detail section taken as indicated by line l-l on Fig. 9;

Fig'. v11 is an enlarged horizontalV section on line Il-HofFig.7; y

Fig. 12 is a View similar to Fig. 8 and showing a modification;

' Fig. 13 is another similar view of the modifi- 3 provided with inter-engaging and interlocking coupler or draft lock elements which are engaged and locked together when the tractor backs under and lifts the forward end of the semi-trailer. The inter-engaging draft lock elements commonly include a king pin and a king pin draft lock, the former commonly being mounted on the tractor and the latter on the trailer, but not necessarily so. That arrangement is used in the present typical illustration of my present invention.

The temporary support for the forward end of the semi-trailer is usually mounted upon and under the forward part of the trailer frame, the rear end of which is supported upon a pair of wheels. The temporary support is raised and lowered with reference to the trailer frame, being adapted to support the forward end of a trailer when lowered. And the coupler and support are usually interconnected for cooperative operation. The accompanying drawings and the following description presupposea general organization of the type described. When I speak of a trailer frame I mean to include in that term any structure, such as a trailer body, which performs the frame function.

Referring to Fig. 4 and following I iirst describe my improved type of support and its operation. Certain features of my invention relate to improvements in the drop leg form of support; other features of my invention are not necessarily limited to that particular type of support, as will appear from what follows and from the subj oined claims.

As shown in the drawings I provide two oppositely disposed supports 2B at opposite sides of trailer frame 2l. Each of these'supports embodies a vertically disposed casing 22 which forms a housing for lifting and lowering mechanism and also forms a guide for the movable supporting member, here shown as the drop leg 23, the latter carrying atits lower end a suitable ground engaging element, preferably in the form of a pair of wheels 24. .A s here illustrated, the two wheels are carried at opposite ends of a trunnion member 25, and that member is mounted on the lower end of leg 23 through the medium of a pivot pin 26 about which the trunnion member and wheels may oscillate to obtain good ground bearing. Either the trunnion member 25 or the lower end of leg 23, or both, may be provided with vertically-spaced openings for the insertion of pin 26, so that the vertical relation of the leg and its lower ground contacting element may be adjusted to suit different `trailer heights. In the drawings the vtrunnion member is shown provided with two such holes 2l. Both these holes are olset from the axis of the wheels; so that additional height adjustment may be obtained by vertically reversing the trunnion member.

The drop leg is here vshcnvn as being 'generally in cylindric tubular form,"and the lower portion 22a of casing 22 is of corresponding general cylindric form so as to form a vertical guide for the drop leg. In order that the guide casing 22a may extend down on the drop leg as far as is practicable, the lower parts of 22a are provided with two opposite notches 39 extending upwardly from its lower edge and adapted to take trunnion member 25 when the latter is in an upper position such Aas is shown in Fig. 8. And to strengthen and reenforce the lower casing portion 22a against longitudinally imposed thrusts, that part of the casing is provided withhollow reenforcing ribs 3l, as illustrated. Guiding lugs Sla, on the leg, ride in the hollow ribs to prevent rotational displacement of the leg. The upper head portion 22D of the casing is preferably integral with the lower guide portion 22a and is enlarged to accommodate the crank-like operating and locking member or dog 32 which is mounted on stub shafts 33 and 34 in suitable bearings in casing head 2211. The axes of the crank shafts of the two opposed supports are arranged in transverse alinement across the trailer frame; and the two operating dogs are interconnected by a single transverse operating shaft 35 in a manner which will be subsequently explained.

Support casings 22 are preferably mounted on the underside of trailer frame 2| through the medium of welded plate structures such as illustrated. Plates 40, in longitudinal vertical planes, arewelded along their upper edges to the under faces of longitudinal frame members Zia, and welded along their lower edges around the tops of casing heads 221). Stiffening flanges l are welded along the edges of plates 4i). Each casing head 22h is provided at its inner face with a pair of spaced vertical flanges 42; and a pair of transverse bracing plates 43 extend between opposite flanges 42 and are welded to them. To additionally stien the structure transversely, bracing plates 44 may be welded at their lower edges to one of the plates 43 and at their upper ends to a transverse frame member 2 l b- Each leg 23 comprisesan upper tubular portion 23a, and a lower portion which may be described generally as comprised of a pair of spaced extending lingers 23h which take trunnion member 25 between them. The tubular wall of the upper portion of the leg is preferably slotted as shown at 45 to accommodate the lifting chain 4S which is attached at its lower end to the lower part of the leg (as by the transverse pin 4l) and is attached at its upper end at 48 to a lug which projects from the throw or clogging portion 32a of the crank-like member 32.

The outer face 3217 of the throw or dog 32a is preferably curved to a surface substantially concentric with the crank center; and this dog is adapted to throw over any one of several stepped locking shoulders 5B, 5| and 52 which are formed on the upper portion of the tubular leg.

Fig. '7 shows the partsV with the leg in its lowermost position and with the dog 32a standing in such a position as to overlie vthe uppermost locking step 52. The length of chain 46 is such as to allow the leg to drop to a position such as that illustratedy when the dog is ina position such as illustrated, substantially directly below its shaft axis. It is not necessary that the clog be definitely limited against moving further to the right beyond the position shown in Fig. '7. The contact of chain 46 with the second step 5l will usually limit the dog to approximately the position shown; and in any case contact of lug 48 with the top step 52 will prevent the dog from throwing clear past the upper step.

To raise the leg the dog is rotated in a clockwise direction, in the aspect vshown in Figs. 5, "I and 8, and, withthe design proportions such as illustrated in the gures, the leg reaches its uppermost position shown in Fig. 8 when the dog is in substantially the position there shown. In this position the upper parto'f the legextends upwardly between the opposite arms 32d of the crank formation. This .provision allowsthe leg to be raisedV to thetopof theY casing; its upward movement not being obstructed by the' operating dog. This vprovision minimizes the necessary 'vertical length of the casing." And withV the leg close to or substantially engaging the top of the casing, all the thrust is taken directly bythe casing in the event that the trailer should be dropped when the legs are up, in such position as shown in Fig. 8. No strain is put on any other of the parts of the mechanism.

To lower the leg the dog is rotated counterclockwise from the position of Fig. 8 toward the position of Fig. 7. Assuming that the ground wheels do not strike the ground before the leg drops to its lowermost position (Fig. 7) then the dog can rotate to its ultimate position shown in Fig. 7. Assuming however that the ground wheels strike the ground at a substantially higher level then, depending upon that relative level, the forward edge or nose 32C of the dog may strike the riser surface 52a below top step 52, or the riser surface la below thenext step 5l, or may even in extreme cases strike the side surface 59a of the leg below the lowermost step 50.

Fig. '7a shows the parts in an illustrative position where the leg has dropped farl enough to allow the dog 32a to move to a position above lowermost step 50, nose 32e having struck riser 5l a below the next upper step 5i.` In this View the relative angular displacement of nose 32o from its position of Fig. 7 v(where it has moved on over the uppermost step) is indicated diagrammatically by the angle a. If the situation is such that the leg drops only so little that nose 32o brings up against the lower face surface 50a of the leg. and do-es not move in over any locking step, (see dotted line position marked 32!) then the relative angle of displacement from the ultimate position shown in Fig. 7 is the larger angle A2. But if the leg drops far enough that nose 32e can move over a step, such as 5l, above lowermost step 5D, then the angle of relative ydisplacement becomes smaller than that shown at a.

Whenever the `nose of the dog is able to move over any one of the locking steps. the leg is thus positively locked down in a position which depends on the level of the particular locking step. If the nose 32C strikes surface 5ta below the lowest locking step, then the leg is not locked down at all. It is, among other things, the function of certain mechanism to be hereafter described to insure that the locking Ydog is positively moved to at least its first locking position and preferably to its ultimate possible locking position in each instance as the co-upler is opened, and to prevent the full opening of the coupler in case either leg has not dropped far enough to be locked on some step by the locking dog. However, the supporting leg has certain inherent advantages and may be used without any special interlocking or operating mechanism, other than some suitable arrangement for raising and lowering the leg or legs by rotating the dog or dogs. Thus, where two supporting legs are used, itmay be supposed that the stub shafts 33 of the two dogs are directly and positively interconnected by the operating shaft 35. Any suitable ymeans can then be applied to shaft 35 to rotate it clockwise to raise the legs, and either to free it to allow the legs to drop or to rotate it counter-clockwise to lower the legs. Such a means maybe either manually or power operated; the latter is shown typically in Fig. 5 asa cylinder 1,35! with piston i3| with its rod 32 connected to an arm 133 fixed on shaft 35. Piping |3ila and 13th may 'admit pressure or vacuum tothe kcylinder ends to rotate shaft 35 ineither direction'or the piston 6 may be operated only to rotate shaft 35 clockwise 'to raise the legs, relief of the pressure then simply freeing the shaft and dogs to allow the legs to drop.

The support mechanism, as so far described, may operate as follows. Assume lirst that the parts are in the raised position of Fig. 8the dog being in the dotted line position denoted 322 in Fig. 7a. The parts are held in that position by the force exerted by the leg raising mechanism; or may be alternatively,`or additionally, held there by any suitable lock (one is described later.) If shaft 35 is then either simply released, or is positively rotated counterclockwise, the leg will lower either to its limiting position (Fig. v8) or to a higher position at which the wheels contact the ground. If the leg is simply dropped, then the falling leg pulls the dog around; and if the wheels and leg stop in an intermediate position (e. g. full line position shown in Fig. 7a) then the dog throws on around by momentum until it strikes one of the vertical step surfaces, say 5| a as in Fig. '7a. If shaft 35 is being positively rotated, thenA the dog is positively moved around until it has reached the same limiting position. Whether shaft 35 be simply freed or positively rotated, the dog in every instance will move around as far as it can go, to take a locking position above one or the other of the locking steps 55, 5l and 52 whenever the leg drops far enough;

In event the leg does not drop far enough for the dog to swing over the lowest step 50, as shown in Fig. 7a, then the dog brings up against the vertical surface a below that step and the leg is not locked at all; the dog being in the relative position denoted 32! in Fig. '7a. In that event, 4with the dog nose 32o against face 59a, the dog is angularly displaced from its lirst locking position (full lines Fig. 7a) by the angle A3. That angle, which becomes or determines the safety margin or angle of the mechanism, may be made as reasonably large as desired, depending as it does on the width of the rst locking step 5G among other things. displacement of the dog from its first locking position may be utilized either as an indicator of non-locking or as a controlling factor in the operation of the interlock which controls the draft coupler, as later described.

Figs. 12 to 14 show a modification in which the leg may be forced down to its first locking position by forced rotation of the dog. The mechanism shown in these figures is the same as that shown in the figures previously referred to, but with the addition of a camming lug (or a pair of such lugs at opposite sides ofthe slot e5 which accommodates the chain). These camming lugs have upper cainming faces Si i'preferably arranged at such an angle as yshown in the drawing. The inner ends of faces Si intersect lowermost step 53 at the point 9'?. at the outer edge of 'step 5l).

The operation of this modified form is the same as before described, but with an additional function if the leg should stop in the position of Fig. 13 or higher. If anything obstructs the drop of the leg between the positions of Fig. 12 and Fig. 13, then enforced rotation of the dog, pressing down on surface or surfaces el, will force the leg down to a position :where the dog can pass the position of Fig. 13 and move in overllowermost step 59; providing of course that the resistance to ieg movement and the force applied to the dog are such that the'legcan be forced down. Once having passed the position of Fig. 13, the dogis then in its rst locking positionfcorresponding to And that relative angular that'previoushf described. In-the position of Fig.

13, -or any position'to the left of that,theleg-is not locked down. The dog position shown in Fig. 13 corresponds to the dog position shown in dotted lines at ,32l in Fig. 7a, in which the leg is not locked down. The angular relationship of the several dog positions, Vand the safety angle, are therefore the same in Figs. 12 and 13r as in the Vother figures previously described. The` dog may be forcibly rotated in a `leg lowering direction either by the leg lowering and raising mechanism, orby action of theinterlocking mechanism `as described later.

As shown in Fig. 14 the two camming legs 9U may be accommodated in an enlarged lhollow rib structure Sid of the casing 22, and may thus act as `splines to prevent rotation of the leg about its vertical axis. n

It may be noted, before going to a further description of the preferred operating mechanism, thatA when the locking dog is in a position lying overany one of the locking steps and the trailer is lowered onto the supporting wheels 2li, the upward thrust of each leg, transmitted to the locking dog, is nally taken by the two stub shafts 33 and ,34 of the cranky formation. The weight thrusts are thus distributed in a balanced relation with respect to the vertical axis of the leg, andare distributed through both sides of casing head 22h to the frame of the trailer.

I have specifically described the leg as being provided with the stepped series of locking shouldersand the rdog as having only one locking face. It will be readily understood, however, that either one of these two relatively movable parts may carry the stepped locking shoulders and the other carry the single locking face. The operation Y will be the same in either case.

. Fig. shows an arm EE secured to shaft 35. Assuming for the present that shaft 35 is rotationally fixed with relation to the dog of Figs. 7 and 8, then arm l lies in the full line position of Fig. 5, on line A, when the dog is in its ultimate position ,with the leg fully lowered as shown in Fig. 7. Arm lil then lies in the dotted line position of Fig. 5, on line C, when the dog is in the position of Fig. S with the leg fully raised. The angle between A and YC and Fig. 5 is the angle b of Fig. 7a. When the dog is inits first locking position, as shown in full lines in Fig. 7a, arm 'lil lies on line B of Fig. 5. between lines A and B corresponds to the angle a in Fig. 7a; and the angle between lines Band C in Fig. 5 corresponds to the angle c in Fig, 7a.

Linkage consisting of a connecting link l'l, a

bell-crank lever 'l2 and a link '13, connect arm 'lil with a longitudinally movable rod ld. The particulars of the connecting linkage are of no irrportance; it is sufficient to observe that the end of rod 'i4 takes the three positions indicated Ai, BI, and Cl when arm l lies, respectively, `in the three positions A, B and C.

The forward part of rod 'i4 is shown in Figs. l and 2. Its position as shown in Fig. l, to the rear, corresponds to the positions denoted Ci and C ilrFig. 5, With the dog in the position of Fig, 8 l

and with the leg fully raised. The position shown in Fig. 2, with rod 74 forward, may correspond either with positions Bl and B of Fig. 5, or with positions AI andv A of that figure. `For the purpose of first describing one mode of cooperation between the support and the draft coupler, it will be assumed that the position of Fig. 2 corresponds IThe angle in Fig. 5

scales of the-drawings are such rthat the :dimension labelled cl in Fig. is equal to the full throw of :the rod 'M between its two positions shown in Figs. 1 and .2.y With this assumption the position of Fig. 1 corresponds to the position of Fig. 8 with the leg .fully raised, and the position of Fig. 2 corresponds to the position of the locking dog shown in full lines in Fig. 7a, in locking position over the rst locking step 5B.

Figs. 1, .2 and 3 show the forward end of the trailer frame 20, provided with a plate |00 on its under side. Alongitudinal slot ll admits the king pin |02 to move backagainst its closed rear. end 103. In that position the king pin is held by a swinging coupler jaw |04 pivoted to plate wil at |05. In the closed position of coupler jaw Hill its outer end lies behind a spring pressed latch H25, normally projected by spring lill. A latch lever |08 is connected with the latch and lies .in the full line'position of Fig. 1

adapted to be hooked up and over the upper edge of opening lll, Vor over a projecting lug Illa at thatedge.

When bar HB is manually pulled forwardly and hooked up in the'position shown in Fig. 3, latch lever `|98 is thrown to the positionshown in Ydotted lines in Fig. 1 and .the beveled nose of the latch is withdrawn to the position shown in dotted lines in that ligure. In this position of Ythe latch the nosev 1Mb of coupler jaw IM inV swinging around toward the open position shown ,in Fig. 2 `will wipe by the .latch and temporarily press the latch back a little further than .thedottecl line position of Fig. l. In doing4 that, banli will be moved forwardly far enoughto release hook H2 from lug Hla, and

gagement, with Illa. Consequently, when the coupler jaw has passed by the latch toward its to .the positions Bl and B ofFig. 5; in other words it willrbe for the presentassumedfthat the relative open position, the latch will return to its normal projected position as shown in Fig. 2, ready to reengage the coupler jaw and lock it closed whenever .the coupler jaw is subsequently thrown .to its `,closed position. In closing from the position ofv Fig'. 2 to that of Figi, the bevel iMa.

f presses the latch back to allowthe coupler jaw to pass behind the latch andthus reach the looked position shown in Fig. 1.

A control arm H5 is pivoted at l i6 on plate ll and isconnected to slide rod 14 in such a manner that, in the movement of that rod between the two positions of Figs. 1 and 2, control Varm H5 swings between the two positions shown in Figs. 1 and 2. That is, control arm H5 is in the position of Fig. 1 when the operating shaft 35 of Fig. 5 is in its position C corresponding with the position shown in Fig. B-with the leg raised to its upper position;V and the control arm l l5 is in the position shown in full lines in Fig.

" .2 when operating shaft' 35 is in' its position B of Fig.' 5-f4thelegis ,down and locking dog 32a has rotated to the vrst .locking vposition shown in full lines in Fig. 7.o.,

The natureof .the connecting linkage ,between Irodfll andarm H5 is not important. VRod "I4 9 is here shown with a cross guide head 14a which takes a pin IIa that projects upwardly from a bracket on the upper face of arm I I5.

The coupler jaw |04 has an extension IMC which is in a position to be struck by king pin |02 as the king pin moves back through slot IOI, so that as the king pin moves back to the position of Fig. 1 it throws the coupler jaw closed. The coupler also has a connecting arm I I'I which is conveniently formed as an extension of the projection I04c, and this connecting arm II'I carries a locking head I|8 at its outer end. Arm |I'| lies under the control arm |I5, and head II8 projects up from arm II'I so that the head lies behind the rear face of arm ||5. Seeing also that arm ||5 lies at a level below rod I4 and below the linkage which connects that rod with arm I I5, the locking head I I8 may swing between lthe positions shown in Figs. 1 and 2.

The inner face IIBa of head IIB is preferably substantially concentric with pivot |05; and control arm ||5 has at its outer end an arcuate face I I5b which also lies in a position preferably substantially concentric with pivot |05 when arm I I5 is in the full line position shown in Fig. 2. And in this position of arm II5, the arcuate face I|5b has -a radius from pivot |05 which is substantially equal to the radius of head face ||8a with relation to that pivot. Thus, in the position of arm` I5 shown in Fig. 2, locking head IIS can swing over face II5b to reach the position of Fig. 2; and, having reached that position, head II8 then positively locks arm I I5 from returning to the position of Fig. 1. Consequently, with the coupler in the open position of Fig. 2, control arm |I5 is locked in such a position that connecting rod 'I4 is locked in its stated forward position. And with rod 14 locked in its forward position the looking dog 32a is locked in the full line position of Fig. 7a over the lower locking step 50 of the leg.

The rear edge face of control arm |I5, behind which looking head I I8 lies in the position of Fig. 1, has a cam formation which cooperates with head |I8 to perform Ycertain functions. That edge face has a rather sharpv concave curvature or Ybend at |20- which lies immediately adjacent the forward end I |8b of head ||8 when the parts are in the position of Fig. 1. In that position vhead I I8 lies close to the pivot end of control arm I I5, andthe arm surface at |20 then lies ahead of head I I8 at such an angle (with relation to the line of the forward swinging of head I|8 and with relation to pivot II6 of arm II5) as to form an effective stop to the forward movement of head |I8. It is not necessary that the formation to the rear by the force which holds the legs in their upper positions, head IIB is effectively locked in the position of Fig. l, and coupler jaw |04 is thus effectively locked in the closed position independently of, and in addition to. the lock which is effected by latch |05.

' From the abruptly curvedportion |20, the rear edge surface of arm |I5 continueson outwardly to the outer end of the arm through a surface I2I which, with arm I|5 in the position shown in Fig. 2 lies at a rather small angle to the forward line of movement of head IIB. Thus, if for any reason arm I|5 should only move forwardly to such a position as shown in dotted lines in Fig.`

2, then head I|3 will strike face |2I at a small acute angle, and further forced forward movement of head II 0 toward its iinal forward position will force arm II5 forwardly to the full line position of Fig. 2 where head IIB canride over the outer arcuate end face |I5b of arm I I5. In or about the dotted line position of Fig. 2, the relation of pin II5a to cross head 'Illa also plays a part. In such a position, the forward movement of rod 'I4 for unit angular movement of arm I I5 is becoming smaller as the full line position of Fig. 2 is approached; sothat an opening of the coupler tends to have greater forcing advantage over a force tending to hold rod 'I4 back. As will be later described, this forcing movement forces the locking dog to its locking position, and, in the form shown in Figs. 12-14 also forces the legs down.

Generally speaking, the controlling arm II5 and locking head |I8 and their connectionsy to rod 'I4 and the coupler may be described as a linkage connecting the support mechanism and the draft coupler and having the functions of (1) giving a Very large or even innite leverage advantage to a force tending to hold the support up, over a force tending to open the coupler, when the parts are in the position of Fig. 1; (2) giving a coupler opening force an increased advantage over a force tending to prevent lowering or locking movement of the. support (tending to resist forward movement of rod 14) as the parts move toward the position of Fig. 2; (3) giving the coupler opening force a Very large or infinite (locking) advantage over any force tending to move rod I4 rearwardly, when the parts arrive in the position of Fig. 2.

. Still describing the operation on the assumption that the full line position of Fig. 2 corresponds withthe rst step locking position shown in full lines in Fig. 7a; then a position such as shown in dotted lines in Fig. 2 corresponds with the locking dog position shown at 32| in Fig. '7a orto the position shown in Fig. 13. In neither of these positions is the leg locked down, but if in Fig. 13 the leg can be forced down or if in Fig. 7a the dog can be moved over lower locking step 50, the opening of the coupler from the dotted line position to full open position will necessarily force the movements of the dog into its first step locking position and, in Fig. 13, will also force the leg down. On the other hand, if in Fig. 13 the leg cannot be forced down, or if in Fig. 'la the dog has brought up against leg face 50a below rst step 50, then the coupler will be positively held from opening, in about the position shown in dotted lines in Fig. 2. This relative position of the coupler is determined, in the present mechanism, by two factors; by the relative angular swing of the coupler to reach its full open position (Fig. 2) after locking head I I 8 has passed off cam face I2I and onto concentric face II5b, and by the safety angle A3 of Fig. 7a which determines the angular relationship between the full line and dotted line positions of control arm ||5 in Fig. 2. By making` the rst mentioned angular swing rather long the leg or locking dog is forced into final locked position by an ample margin before the coupler is wide open. By making the safety angle rather large, the coupler is held, by the non-forcible locking dog, in a position well ahead of the passage of locking dog I I8 Il. onto-arm surface H517; so that ample margin is provided to insure coupler holding in'splte of inaccuracies` and tolerances in the. mechanisms, and so that the coupler jaw wt is held in such a well closed position as shown in dotted lines in Fig. 2. These provisions of ample margins also make it practicable to use a cable for the connec- .tion between arm 10 and the controlling arm H5, the marginsproviding amply for cable stretch.

The foregoing describes how the leg is either locked on its rst step or the coupler is held from opening. I have previously described how the dog will .usually be thrown around by momentum either to its ultimate locking position (Fig. '7) or*V until it brings up against one or the other of the vertical surfaces of the leg, depending on how far the leg has been moved down or has dropped. Inany circumstances wherethe dog is thus moved to or past its first locking position l (full lines in Fig. 7a) to lock on any of the locking steps, the control arm H5' will move to or past the fullline position of Fig. 2, and thus free the coupler for free opening.

In addition to the described means for moving the legs upwardly and holding them in upward position, I provide apositive locking means for locking the legs in or near their upper position until manual release has occurred. As has been explained, lowering of the legs is necessarily accompanied by forward swinging movement of control arm H5. A pivoted dog 135 is mounted on plate IBB in a bracket 36 and in such a position that dog nose l-3 will normally lie in the path of the outer end of arm H5 to prevent the arm from swinging forwardly far enough to lower the legs substantially. The dog is held in itsnormal position by a spring 38 and in that positionY the shoulder i3d on the dog engages bracket 13S to prevent the dog being moved when arm IIS strikes it.- An operating rod M is connectedV to the dog, passes loosely through lug |41 on latch arm 198, and has a head |42 on its endin such a position that dog 35 willl be retracted tothe dotted line position of Fig. 1 when latcharm 98 is movedto its cocked position shown in dotted lines vin Fig. 1.

Thus, dog |35 prevents the leg lowering motion to control arm H until latch |06 has been manually Vwithdrawn to release the latch lock of coupler jaw 104. Until thatloperation is manually performed, arm H5 cannot move forwardly and the legs cannot be moved down. In Ythe described condition of the parts the coupler is freed to be opened insofar as latch 50S isconcerned, but it is still held locked in its closed position by control arm H5 until that arm has been moved forwardly by lowering of the legs. Consequently, it is then necessary to lower the legs, at least far enough to put the coupler mechanism in such a position as shown in dotted lines in Fig. 2, before the coupler can be forced open.

The foregoing description of operation has been based on the assumption that the interlocking and controlling mechanism is positively coupled to the leg lifting and locking dog, without any lost motion. I prefer however to introduce a lost motion in the interconnection, primarily to cause the locking of each of the opposite support legs in the lowest position to which it has moved, to take care of situations where the legs dro-p unequal distances to Contact the ground. The provision of that lost motion also has a desirable effect on the locking of the legs by opening of thecoupler, as will be explained. A suitable lost motion arrangement is now described, and a de- 12 scription of operation with the lost motion then follows.

Transverse operating shaft 35 is connected to thestub shaft 33 of each support through the medium of a lost motion connection such as that shown in detail in Figs. 9 and 10. The operating shaft 35 carries at its end asleeve 68 rigidly secured to the shaft as by welding. Sleeve Si) projects from shaft 35 and surrounds the projecting end of stub shaft 33, being rotatable on and with reference to 33. The end 33a of shaft 33 projects into the interior ofl sleeve Sib and carries two angularly spaced shoulders 331i and 33o adapted to be engaged by a lug 63o: which projects between them from sleeve 66. A coiled spring Si may be attached at one end 31a to shaft 36 and at the other end at `lb to stub shaft 33. If the spring is used it is pre-stressed in such a direction that it tends to rotate shaft 33, with relation to shaft 35, in the relative direction indicated by the arrow which is placed on shaft 33a in Fig. 9, tending to keep shoulder 33h against lug 6ta. The direction of rotation of shaft 33 to lower the leg is counter-clockwise in Fig. 9,. as indicated bythe large arrow lying outside sleeve 6B. That is also the direction of rotation of sleeve 59 and of operating shaft 35 to lower the leg; and the spring tends to make shaft 33 and the dog follow the lowering rotation of shaft 35 with the lost motion closed as shown in Fig. 9; and allows sleeve 6U and shaft 35 to rotate on through a limited angle ahead of 33a and the dog if'the dog is stopped.

When the system includes such a lost motion provision, then the proportional dimensions and angular movements of the parts are made such that the movement of arm 'il inl Fig. 5 between its extreme positions indicated by lines A and C (and the movement of connecting rod 14 between the positions indicated at A1 and C1 in Fig. 5).corresponds to the movement of control arm H5 between the position shown in Fig. l and the position shown in full lines in Fig. 2. That is, the relative scales of Fig. 5 and of Figs.

1 and 2 are now taken to be such that the dimension bl of Fig. 5 is equal to the movement of orosshead 'Ida between the full-line positions of Figs. 1 and 2. The position of control arm H5 in Fig. 1 corresponds with position C of arm 'I in Fig. 5, and with the fully raised position of the dog shown in Fig. 8 and shown in Fig. 7a in the position denoted 322. And the position of control arm H5 shown in full lines in Fig. 2 corresponds to the position A of arm 'I0 in'Fig. 5; and also corresponds to the fully thrown position of the dog shown in Fig. 7, if the dog has rotated through the full angle b with shaft 35 and the lost motion has not opened (lost motion still closed in the position shown in Fig. 9).

With the arrangement as thus described, I will assume first that no springs are used in the two lost motions. the lost motions being merely loose. Itis to be observed that the weights of the legs, hanging on the dogs 32a, tends to rotate the stub shafts 33a relatively in the same directions as do the springs, and tend to keep the lost motions closed in the relative positions shown in Fig, 9. The angular lost motion movement, indicated at al in Fig. 9 is made equal to or just slightly greater than the angle a ofFlg. 7a. The latter angle is the relative displacement angle of dog 32a between its fully thrown position of Fig. 7 and its position in which it bring-s up against vertical leg face 5 a in a position to lockingly engage over the lowest locking step Ell-the position shown in full lines in Fig. 7a. In other words, the lost motion angle provides that if either dog is held up against face la in a position to engage the lowest locking step, the operating shaft 35 can rotate on around through the further angle a and thus rotate altogether through the full angle b of Fig. 7a. Thus, either or both the dogs can stop in the full line position of Fig. 7a, and operating shaft 35 can rotate ahead of the stopped dog or dogs to allow control arm H5 to reach the full line position of Fig. 2. For the dog which is stopped in that position, its lost motion will then have opened to a limit of the angle al (and angle a of Fig. 7a). And if either leg has dropped further so that the one dog can throw further toward the ultimate position shown in Fig. 7, then that dog may and usually will be thrown to its furthest possible position by momentum in the manner before explained, and will thus be in a position to lockingly engage one of the higher steps of its leg. Thus, in any situation where both legs drop at least far enough to allow the dogs to move to locking position over the lowest locking step, control arm H5 moves, or can be moved freely, to the full line position of Fig. 2 allowing the coupler to open. In such circumstances, the opening of the coupler will move control arm H5 to the full line position of Fig. 2 and forcibly move the dogs at least to their first locking position (full line position of Fig. 7a) if they have not already been thrown to or past that position. And in Figsl2 and 13, this forced movement of one or both dogs 'will necessarily force one or both legs down to the rst locking position. Just as in the first described system which has no lost motion, the dogs are positively forced to their rst locking positions, and in Fig. 12 the leg is forced down, by virtue of the king pin movement which opens the coupler.

In the event that either of the legs does not drop far enough to allow its dog to move over the lowest locking step v50 then that dog, being up against leg surface 50a below step 50 will be held in the position shown in dotted lines at 32E in Fig. '7a. In that stopped position the dog will be held, by the amount of angle a2 of Fig. 7a,

' from travelling through the full angle b; or, to

put the matter another way, the dog will be held, by as much as the safety angle a3, from travelling through the angle c which represents the angle through which the dog must travel if shaft 35 travels through the full angle b and the dog lags behind by the maximum angle a allowed by the lost motion. Consequently, if either dog is held up against face a, operating shaft 35 is held by safety angle a3, from reaching its position of full rotation through angle b, and control arm H5 is then positively held in approximately the position shown in dotted lines in Fig. 2. And with the control arm positively held in that position, the coupler cannot, open as before explained. The same result obtains in Figs', i2 and 13 if the leg cannot be forced down far enough to allow the dog to move over the first locking step.

If the springs Si are used in the lost motions, tending to keep them in the closed positions shown in Fig. 9, then the operation of the whole system is the same as has been described, eX- cepting that if either or both of the dogs can move past the first locking position (full lines of Fig. 7a) they will be so moved under the pressure of the springs. As has been stated. both dogs will be positively moved as far as that position of Fig. 7a if control arm H5 reaches the full line position of Fig. 2. In that condition the lost motions are still closed, and the further rotation of operating shaft 35 through the angle a opens one or both of the lost motions and applies the spring pressure to the dog to move either or both of them over a higher step if that is possible.

I have said that certain features of my invention are not necessarily limited to a support of the sliding drop-leg type. The stepped locking shoulder formation and the progressively movable locking dog with or without its lost motion actuation is applicable to a movable support element whether that element moves directly along a vertical line or, more broadly, has movement in a vertical direction. Consequently, when I describe the leg or supporting element as moving vertically I do not intend limitation to'movement directly along a vertical line, but only to movement which involves a vertical component.

And I do not conceive of my invention as being necessarily limited to a swinging locking dog. The locking action of the dog, operating on either one locking shoulder or on a stepped series of locking shoulders, is an action involving movement of the dog in a direction transversely of the movement of the supporting element. Whatever the particular movement ofthe dog may be, that movement may be transmitted to the supporting element to lift it. As an instance I show diagrammatically in Fig. 15 how a horizontally sliding dog 32e can move in one direction to engage the locking steps on a vertically moving leg 23e, and lift the leg through a chain or other flexible connection 45e when the dog moves in the opposite direction.

I claim:

l. Support for a. semi-trailer or the like; comprising the combination of a movable supporting element, relatively stationary framing means including means for mounting said supporting element for vertical movement with relation to the trailer, the movable supporting element having a locking shoulder lying in a plane transverse of its direction of movement, and a locking dog directly mounted on the relatively stationary framing means and movable thereon in a direction transverse of the movement of the supporting element toward and away from that element to be engageable with the disengageable from said locking shoulder.

2. Support for a semi-trailer or the like as defined in claim 1, and in which the locking dog is swingingly mounted on the framing means and has swinging movement along a line transverse of the direction of movement of the supporting element.

3. Support for a semi-trailer or the like as dened in claim 1, and in which the supporting element is in the form of a vertically sliding leg guided by the mounting means, and in which the locking dog has movement horizontally.

4. Support for a semi-trailer or the like as de# fined in claim 1, and also including a lifting connection between the dog and the movable supporting element whereby that element is lifted by movement of the dog away from'it.

y 5. Support for a semi-traileror the like asv de# lined in claim 1, and in which the supporting element is in the form of a vertically sliding leg guided by the mounting means and having its locking shoulder at'its upper end, the locking dog is swingingly mounted on the framing means on a'transverse axis above the sliding leg, the dog being adapted to engage the vleg shoulder when the dog is in a position below its axis, and a nonthrust-transmitting lifting connection between the swinging dog and thev sliding leg whereby the legis lifted when the dog is swungv upwardly about its axis.

6. Support for a semi-trailer or the like as dened in claim 1, and also including means interacting between the supporting element and the locking dog whereby the supporting element is forcibly moved by virtue of movement of the locking dog in its direction to engage with said locking shoulder.

'7.` Support for a semi-trailer or the like as dened in claim l, and also including cam means interacting between the supporting element and the locking dog whereby the supporting element is forcibly moved by virtue of movement of the locking dog in its direction to engage with said looking shoulder.

8. Support for semi-trailer or the like as dened in claim l, and also comprising motion transmitting means connected to the locking dog and including a lost motion.

9. Support for semi-trailer or the like as dened in claim l, and also comprising motion transmitting means connected to the locking dog and including a lost motion, and an elastic element in the lost motion tending to take up the lost motion in a direction which causes movement of the locking dog toward the supporting element.

l0. Support for a semi-trailer or the like; comprising the combination of framing means, and trailer supporting means comprising two elements, one of said elements being in the form of a supporting element mounted in the framing means for vertical movement with relation thereto, the other element being in the form of a horizontally movable locking dog directly mounted on the framing means, one of said elements having a horizontal locking shoulder and the other element having a cooperating series of horizontal locking shoulders arranged in a stepped formation inI which the several locking shoulders are mutually spaced both vertically and horizontally, the several shoulders of the stepped series being successively engageable by the first mentioned locking shoulder by successive horizontal movements of the locking dogtoward the supporting element.

11. Support for semi-trailer or the like as dened in claim l0, and also including a nonthrust-transmitting lifting connection between the dog and the movable supporting element whereby that element is lifted by movement of the dog away from the supporting element.

12. Support for semi-trailer or the like as dened in claim l0, and also comprising motion transmitting means connected to the locking dog and including a lost motion element whose extent of lost motion corresponds substantially to the movement of the locking dog between its two positions in which it respectively engages the rst and last of the series of stepped locking shoulders.

13. Support for a semi-trailer or the like; comprising the combination of framing means including a guide casing, and trailer supporting means comprising two elements, one of said elements being in theform of a vertically sliding leg guidedvby said casing, the other element being in the form of a horizontally movable locking dog directly mounted on the framing means, one of said elements having a horizontal locking shoulder and the other element having a cooperating series of horizontal locking shoulders arranged in a stepped formation in which the several locking shoulders are mutually spaced both vertically and horizontally, the several shoulders of the stepped series being successively engageable by the rst mentioned locking shoulder by successive horizontal movements of the locking dog toward the leg.

14. Supporting means for a semitrailer or the like; comprising the combination of two supports mounted in spaced opposition on the trailer frame, each said support comprising two supporting elements, one of said elements being in the form of a movable ground engaging member movable in a vertical direction with relation to the trailer frame, the other of said elements being in the form of a locking dog movable in a, direction transverse of the direction of movement of the ground engaging member, one of said elements having a locking shoulder in a plane transverse of the direction of movement of the ground engaging member, the other of said elements having a cooperating series of locking shoulders each lying in a transverse plane and arranged in stepped formation in which the several shoulders are mutually spaced both transversely of and longitudinally of the direction of movement of the ground engaging member, the several shoulders of the stepped series being successively engageable by the first mentioned locking shoulder by successive movements of the locking dog in its transverse direction of movement, a common operating member for both locking dogs, and a lost motion connection between said common opera-ting member and each of the locking dogs.

l5. Supporting means for a semi-trailer or the like as dened in claim 14, and in which each movable ground engaging member is in the form of a vertically sliding leg, in which each locking do-g is in the form of a swinging dog pivoted on a horizontal axis, and in which the common operating member is in the form of an operating shaft extending between the two opposed supports.

16. Support for a semi-trailer or the like, comprising the combination of a guide casing adapted to be secured to the trailer frame, a vertically slidable supporting leg guided by the guide casing, a transverse locking shoulder on the upper end of the leg, a locking dog in the form of a doublearmed crank mounted across the interior of the casing on a transverse swinging axis which lies in the plane of movement of the vertically sliding leg, said dog adapted to engage the locking shoulder of the leg when the dog lies substantially in said plane of movement, and the arms of crank formation of the dog being spaced apart axially to permit passage of the upper end of the leg between them.

1'7. Support for a semi-trailer or the like; comprising the combination of a support guiding frame adapted to be secured to the trailer frame, a movable support element guided by the frame to move back and forth along a line of movement having a vertical component, a support locking element mounted on the frame to have movement in a direction transverse of the line of movement of the support element, one of said elements having a locking shoulder and the other having a series of cooperating locking shoulders arranged in a stepped formation with the several shoulders spaced both longitudinally and transversely o f the line of movement of the support element, and movement transmitting means connected to the locking element and including a lost motion.

18. Support for a semi-trailer or the like; com- -prising the combination of a support guiding frame adapted to be secured to the trailer frame, a movable leg slidable in the frame in a vertical direction, the upper end of the leg having a stepped formation with a series of upwardly facing locking shoulders which are spaced from each other both vertically and horizontally, a leg locking do-g pivoted on the frame to swing about a horizontal axis and adapted to move in a horizontal direction over the upper end of the leg to successively overlie successive step shoulder of the leg, and motion transmitting mechanism connected with the pivoted dog.

19. Support for a semi-trailer or the like; comprising the combination of a support guiding frame adapted to be secured to the trailer frame,

va movable leg slidable in the frame in a vertical direction, the upper end of the leg having a stepped formation with a series of upwardly facing locking shoulders which are spaced from each other both vertically and horizontally, a leg locking dog pivoted on the frame to swing about a horizontal axis and adapted to move in a horizontal direction over the upper end of the leg to successively overlie successive step shoulders of the leg, a motion transmitting shaft connected with the pivoted dog, and a lost motion means incorporated in said shaft and including a takeup spring which tends to mo-ve the dog in a di-v rection toward the upper end of the leg.

20. Sup-port for a semi-trailer or thev like as defined in claim 18, and in which the motion transmitting mechanism includes a lost motion element whose extent of lost motion corresponds substantially to the movement of the locking dog between its two positions in which it respectively overlies the nrst and last of the series of stepped locking shoulders on the leg.

2l. Support for a semi-trailer or the like as dened in claim 19, and in which the extent of lost motion provided by the lost motion means corresponds substantially to the movement of the locking dog between its two positions in which it respectively overlies the rst and last of the series of stepped locking shoulders on the leg.

22. Support for a semi-trailer or the like; comprising the combination of a leg guiding casing adapted to be secured to the trailer frame and having a lower open end, a sliding leg guided by the casing to move in a vertical direction, the upper end of the leg lying within the casing and its lower end being projectible below the casing, a swinging locking dog of crank-like form mounted across the casing to swing on a substantially horizontal axis, said swinging axis being located above the sliding leg and substantially on its line of movement, the leg and the dog having locking surfaces which are adapted to the interengage to prevent upward movement of the leg when the dog lies in a lower position under its swinging axis, and a flexible connector extending between the dog and a lower part of the leg whereby the leg may be raised by swinging the dog away from its lower position and upwardly about its axis.

23. Support for a semi-trailer or the like as dened in claim 22, and in which the upper end of the leg is provided with a plurality of stepped locking surfaces adapted to the selectively engaged by the locking dog.

24. In a tractor and a semi-trailer combination in which the tractor and trailer are provided with interengaging draft elements including a releasable draft lock on one vehicle adapted to lockingly engage the draft element of the other vehicle, and in which the trailer is provided with a support movable along a xed line of movement between supporting and non-supporting positions; the improvement which is characterized by the trailer support having a series of locking shoulders arranged in a stepped formation in which the several shoulders are mutually spaced both longitudinally and transversely of the line of movement of the support, a transversely movable locking member mounted on the trailer frame adapted by successive steps of transverse movement in one direction to lockingly engage the successive stepped locking shoulders of the support, a movable control member associated with the draft lock and adapted to be positively moved to a predetermined definite position by virtue of release of the draft lock, and connecting means between said control member and the support locking member whereby the latter is positively moved in its transverse locking direction as the control member is moved toward its said pre-A determined position. v

25. Improvements in tractor and semi-trailer combinations as dened in claim 24, and including a lost motion device incorporated in said connecting means, thelost motion allowed by said device corresponding in extent with the movement of the looking member between its positions wherein it respectively engages the rst and last of the successive locking steps on the support.

26. In a tractor and semi-trailer combination in which the tractor and trailer lare provided with interengaging draft elements including a releasable draft lock on one vehicle adapted to lockingly engage the draft element of the other vehicle, and in which the trailer is provided with a support movable along a fixed line of movement between supporting and non-supporting .positions; the improvement which is characterized by the trailer support having a locking shoulder in a plane transverse of the line of movement of the-support, a transversely movable locking member mounted on the trailer frame and adapted by transverse movement to lockingly engage the locking shoulder of the support, a movable control member associated with the draft lock and adapted to be forcibly moved to a predetermined denite position by virtue of opening movement of the draft lock, and connecting means between said control member and the suD- port lockingl member whereby the latter is positively and forcibly moved in its locking direction as the control member is moved toward its said predetermined position.

27. In a tractor and semi-trailer combination in which the tractor and trailer are provided with interengaging draft elements including a releasable draft lock on one vehicle adapted to lockingly engage the draft element of the other vehicle, and in which the trailer is provided with a support movable along a fixed line of movement between supporting and non-supporting positions; the improvement which is characterized by the trailer support having a locking shoulder lying in a plane transverse of the line of movement of the support, a transversely movable locking member adapted by movement in one direction to lockingly engage the locking shoulder of the support, interacting means between the support and the locking member adapted to forcibly move the support into supporting position by virtue of movement of the locking member toward its locking position, a movable control member associated with the draft lock and adapted to be forcibly moved to a predetermined denite'position by virtue of opening; of the shaft lockand connecting means'between said control .l member and the support locking member where- 4byv the latter isforcibly moved in itsV locking direction as the control member is moved toward Y its said predetermined position.

28. In a tractor` and semi-trailer combination in which the tractor and trailer are provided with interengaging draft elements including a reieasable draft lock on one vehicle adapted to `lockingly engage the draft element of the other vehicle; supportingmeans for the trailer comprising-two elements, oneof said elements being `in the form of a movable ground engaging member movable in a vertical direction with relation to the trailer frame, the other of said elements being in the form of a locking dog movable in a direction transverse of` the direction of movement of the ground engaging member, one of said elements having a locking shoulder in a plane transverse of the direction of movementof the ground engaging member, theother of said elements having a cooperating series of locking shoulders each lying in a transverse plane and arranged instepped formation in which the several shoulders are mutually spaced both transversely of and longitudinally of the direction of movement of the ground engaging member, the

i severalshoulders of the stepped seriesbeing successively engageable by the first mentioned locking shoulder by successive movements of the locking dogin its transverse direction of movement toward the ground engagingmember, a movable control member associated with the draft lock and adapted to be positively moved to a predetermined denite position by virtuev of release of the draft lock, and connecting means between said control member and the support lockingA member whereby the latter is positively moved in its transverse locking direction as the control member is moved toward its said predetermined position, said connecting means including a lost motion element whose extent of lost motion corresponds substantially to the movement of the locking dog between its two positions in which the rst and the last of the successive` locking shoulders are engaged.

29. Supporting means as defined in claim 28, and also comprising a non-thrust-transmitting lifting connection between the dog and the ground engagingrmember whereby that member is lifted by movement of the dog away from it.

WALTER BENNETT.

REFERENCES CITED The following references are of record in the le'of this patent:

UNITED STATES PATENTS Number 

